Device for tuning or adjusting to close limits



S. Y. WHITE DEVICE FOR TUNING 0R ADJUSTING TO CLOSE LIMITS Filed Nov. 6, 1942 7 Sheets-Shoot 1 INVENTOR. Sidney Y W/7/f6 AT TORNEYS y 1945- 5. Y. WHITE 2,399,701

DEVICE FOR TUNING OR ADJUSTING TO CLOSE LIMITS Filed Nov. 6, 1942 7 Sheets-Sheet 2 3 l3 s v x INVENTOR. S/dney Wh/fe I v B Q Q BY M g ATTORNEYS May 7, 1946. 2,399,701

' DEVICE FOR TUNING on ADJUSTING TO CLOSE LIMITS S. Y. WHITE Filed Nov. -6, 1942 7 Sheets-Sheet 4 INVENTOR. Sidney )(Wfl/fe BY MM ATTORNEYS S. Y. WHITE May'7, 1946. I

DEVICE FOR TUNING 0R ADJUSTING TO CLOSE LIMITS 7 Sheets-Sheet 5 Filed Nov. 6, 1942 mvauron M 0 w Y W 5 N AT TORNEYS May 7,1946. s, Y, wHlTE 2,399,101

DEVICE FOR TUNING OR ADJUSTING TO CLOSE LIMITS Filed Nov. 6, 1942 V 7 Sheets-Sheet 6 Sid/7e y K White INVENTOR. v

A TTOR/VEYS May 7, 1946. 5. Y. WHITE 2 9,

DEVICE FOR TUNING 0R ADJUSTING TO-CLOSE Lnms Filed Nov. 6, 1942 Sheets-Sheet 1 AT T RIyEYs Patented May 7, i946 -DEVICE FOR TUNIN CLOSE G OR ADJUSTING TO LMTS Sidney Y. White, Wilmette, m. lsslgllol' to Victor S. Johnson, Chicago, 111.; Alex Thomson administrator ceased of said Victor S. Johnson, de-

Application November 6, 1942, Serial No..464,812 19 Claims. (Cl. 14-568) This invention relates to a device for adjusting or tuning to close limits and relates to certain improvements on the adjusting device disclosed in patent application Serial No. 439,509, flied April 18, 1942, in my name. In said application a spacing member in the form or a cam provided with a plurality of steps is interposed between an operated member and an operating member having a limited range of movement which is continuous and finely graded. The operated member is illustrated as the tuning means for tuning a radio circuit and the adjustable gage block of a gage for gaging the size of articles. In the present application, although the invention is illustrated only in connection with the tuning means of a radio circuit, it will be understood that'the'invention is not limited to such use but'that it is of general utility wherever an adjustment of such member to close limits is desired. By rotating thecam it is possible to displace the operated.

or tuning member to different positions relative to the operating member for any given position of the latter, so that the operated member may for any of its p sitions, as determined by the setting of the cam, be moved through a limited range of movement by operation of the operating member. In the herein illustrated form of the invention, the cam is provided with a plurality ot steps adapted to impart successive steps of movement to the operated member, which movements are equal to each other and also equal or substantially equal to the limited range of movement of the operating member. Such relationship is not necessary, however, for the practice of the invention, and it will be understood thatfor certain purposes the several steps of the cam'may be unequal, and also that the limited amount of movement imparted to the operated member by the actuation of the operating member may be more or less than any one step of movement imparted to the operated member in response to rotation of the cam. In the illustrated embodiment of the invention, the operated member is a push rod which carries a powdered iron core, this core being movable within the coil of a circuit of a radio tuner. Each step of the cam is designed to move the push rod a distance of .010 inch and to tune the radio circuit over a range of l megacycle.

It is a purpose of the present invention to provide an operating member'to secure a continuous movement of the tuner push rod or other operated member in the form of a threaded screw having a. fine pitch, the screw operating directly against the cam a' d without the interposition of a lever of the invention the frequency of the resonant or other operating connections between these members. Screws of fine pitch are extremely difiicult and expensive to manufacture with a constant pitch, small variations in the pitch usually appearing from one turn ot the thread to another. Such variations in pitch between the different threads introduce corresponding errors in the setting oi the tuning means in cases where the screw is arranged to be rotated through several revolutions. It is a purpose of the present invention to eliminate such errors in the setting of the tuning or other operated member by limiting the rotation of a fine pitch screw to somewhat less than a lull revolution so that the same identical threads 1 on the screw are always operative in securing the continuous adjustment of the tuning member.

It is a further object of the invention to provide in connection with such fine pitch screw a graduated continuous dial associated therewith, the graduations of thedial being such that the setting 01' the tuning member may be read oi! directly on the dial in kilocycles. This dial is preferably mounted closely adjacent to and concentric with a discontinuous dial which is mechanically connected to the cam and indicates in megacycles the setting of the tuning member as secured by the rotary cam. Thus the two dial readingsmay be easily and conveniently read through the same window opening provided in the receiver casing. As in the case of the aforementioned application, in the illustrated embodiment circuit of the radio tuner may readily be determined by merely adding the two dial readings together.

Where a line pitch screw is utilized to adjust the tuning or other device, for accurate adjustment it is essential that all backlash and other lost motion between the threads 01' the screw and the nut in which the screw is mounted is provided with spaced apart threaded portions which engage regions of the screw threads that are spaced apart by a substantial distance so that any tendency of the screw to move vertically or sidewise in it supporting nut is entirely obviated. Each of such threaded portions of the nut is cut away to form a tongue which projects from the main body portion of the nut, which tongue may be bent slightly inwards so that the threads formed thereon come into firm and intimate contact with the threads of the screw. A non-circular clamp or adjusting ring is provided surrounding each tongue and keeping it continually biased into intimate engagement with the threads of the screw, so that the screw is at all times loaded and all backlash or other lost motion is reduced to the minimum.

As in the aforementioned application, the rotary cam is provided on its rear face with a plurality of balls which come into successive en'- gagement with the push rod 01' the tuning member to advance it step by step. An important feature of the present inventionvrelates to the provision of means for adjusting the thickness of the cam in the region of each ball. For this purpose the front face of the cam is provided opposite each ball with a tapered surface and a correspondingly tapered compensating block is provided which is slidable along such surface for adjusting the thickness of the cam in the region of each ball. In the illustrated embodiment of the invention, each such tapered compensating block is slidable in a groove formed in the front surface of the cam, and means are provided in the form of spring means associated with each block for retaining it in its adjusted position in the groove. In the illustrated form of the invention two springs are provided for each block, one of which biases the block against the bottom wall of the groove, and the other of which biases it against a side wall thereof. It is a cognate object of the invention to so shape and arrange these springs with reference to the compensating blocks that they do not cause any creeping of the blocks in their grooves during the use of the tuning device which would change the setting of the tuning means.

A related object of the invention consists in the provision of means associated with each compensating block whereby it may be adjusted inwardly and outwardly along its groove. In an illustrated form of the invention, the spring which biases the block against the side of its groove is so shaped that its outer end extends beyond the outer end of the block so that a tool may be placed against the end of the spring to adjust the block inwardly along the groove. In one illustrated form of the invention, the outer end of such spring is formed in the shape of a hook, so that a tool may be inserted in such end to pull the spring and block outwardly in its groove if for any reason such adjustment of the block should .be required. The closed casing in which. the cam is mounted is provided with an opening in alignment with the end of one of the springs through which such adjusting tools may be inserted for adjusting the several blocks one after another. A plug is provided for closing this opening to seal the casing. In a modified form of the invention illustrated, the outer end of the block-retaining spring is not provided with a hook shaped end, but the compensating block the invention, the spring fingers which bias the blocks against the bottom of the grooves in which they are seated are provided with curved recesses in their front faces, the curved marginal walls of these recesses coming into engagement with a conical shaped surface provided on the adjusting screw near the end thereof which engages the adjusting blocks. These curved marginal walls on the spring fingers come successively into engagement with the aforementioned conical surface and thus displace the cam rearwardly each time the cam is rotated through one step.

A still further object of the invention resides in the provision of means for minimizing errors in setting of the tuning means due to wear of the end of the push rod which operates such mean and which engages the balls of the cam In the illustrated embodiment of the invention the end of the push rod is provided with a groove having curved side walls which provide two zones of line contact with each ball on opposite sides of the high point thereof. The zones of contact with the ball thus provided are much more extensive than merely point contact therewith, thus reducing the wear on the end of the push rod to a negligible amount.

A still further important feature of the invention lies in the provision of means for resiliently supporting the radio tuner or other device within a substantially closed casing for limited freedom of movement in all directions, so that any shocks or vibrations imparted to the casing are largely absorbed by the resilient supporting means, and thus prevented from affecting the setting of the tuning means. In the illustrated embodiment of the invention, three'resilient supports are provided for the chassis of the radio tuner, one at the rear thereof and two others at spaced apart regions on the front thereof. The resilient supports at the front not only serve to resiliently support the front end of the chassis,

* but also serve as transmitting means for transitself is provided with an opening into which the end of a tool may be inserted to pull the block outwardly in its groove.

A further feature of the invention resides in the provision of means for moving the cam axially during its rotation and while one adjusting block is moving out of engagement with the end of the adjusting screw until the next block comes into engagement therewith, thus preventing the end of the adjusting screw from striking against the side edges of the adjusting blocks as the cam is rotated to adjust the tuning means in steps.

mitting the rotation of two adjusting knobs disposed inv front of the casing to the cam and to the feed screw which operates the tuning member. These resilient supports are so arranged that they transmit only torque to the rotary drive members of the tuner, any vertical or sidewise component of force applied to the tuning knobs being taken up by the front panel of the tuner casing and not communicated to the drive members which serve to operate the tuner. The tuning knobs are designed to conceal such resilient supporting members from view, thus enhancing the appearance of the device. Further and more detailed objects of the invention will become apparent as the description thereof proceeds.

No claim is made herein to radio tuning means, for the reason that such subject matter is claimed in my divisional application, Serial No. 538,347, filed June 2, 1944,- for Radio tuning means.

For a better understanding of the invention, reference is made to the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a front view of a radio tuner embodying the invention;

Fig. 2 is a vertical sectional view of the tuner of Fig. 1 taken on the line 2-2 thereof;

Fig. 3 is a view partly in section showing the driving connections to the adjusting screw of the In theillustrated form of 7s tuner disassembled:

Fig. 4 is a horizontal sectional view of the tuner of Fig. 1 taken on the line 4-4 thereof;

Fig. 5 is a front view with portions cut away showing the drive cam of the tuner;

Fig. 6 is a vertical sectional view of the cam shown in Fig. 5 taken on the line 4-. thereof;

Fig. '7 is a front view, showing on an enlarged scale, one of the cam adjusting blocks and its I v retaining spring;

Figs. 8 and 9 show modified forms of cam adjusting blocks with their retaining springs;

Fig. 10 is a side view of the drive cam ofthe tuner showing also the ends of the adjusting screw and the tuner push rod;

Fig. 11 is a rear view of the cam shown in Fig. 10 also showing the end of the tuner push rod operated by the cam; v

Fig. 12 is an enlarged fragmentary view partly in section showing the adjusting screw, a portion of the cam and the cooperating end of the push rod' with the cam at an intermediate position between two tuner setting positions thereof;

Fig. 13 is a vertical section of the adjusting screw of Fig. 12 taken on the line lL-II thereof;

Fig. 14 is a view of a clamping ring for a nut of the adjusting screw showing its elliptical shape before being placed in' position;

guided in openings :0 and u provided, respectively, in the wall 22 and the rear wall 32 of the die casting 2!. Push rod 24 is biased forwardly II to which the front endof the spring is connected. and which is clamped in position in the bore 34 by a screw II. To prevent rotation of push rod 24 during its longitudinal adjustment, it is provided along one side thereof near its front end with a groove 40 (see Figs. 4 and 12) in which Fig. 15 is a front view showing the front end of the tuner push rod;

Fig, 16 is a vertical section on an enlarged cale taken on the line "-48 of Fig. 4 showing portions of the driving connections to the tuner adjusting screw;

Fig. 17 is a vertical section on an enlarged scale taken on the line "-11 of Fig. 4 sh'owing portions of the driving connections to the cam;

Fig. 18 is a vertical section on an enlarged scale taken on the line |8-l8 of Fig. 4 showing the resilient supporting means for the rear end of the tuner chassis; and

Fig. 19 is a rear view of the. continuous dial of the tuner and its associated parts, with the dial adjusted to its zero position.

Referring to Figs. 1, 2 and 4, the invention is shown in connection with a radio tuner adapted to be tuned to ultra-high frequencies of the order of 100 to 125 megacycles. The tuner is especially adapted formobile use where it may be subjected to shocks and jars caused by rough handling and'to extreme changes in temperature and humidity, the tuner being constructed so that such changes have no effect on its tuning. The chassis ill of the tuner comprises an oscillator tube ll (see Fig. 4) provided with a tunable tank circuit i2 comprising a coil i3 formed of silver ribbon and a condenser i4 of fixed capacity wh'ose ends are connected across the ends of coil l3. Coil I3 is wound in a helical groove formed in a cylindrical tube l5 of ceramic material which is fused to and supported by a rectangular block l8 also of ceramic material. The ends of coil it are soldered to a pair of silver blocks H which are secured to the supporting block I6 by the screws l8 which also serve as theterminals of the resonant circuit. The block I6 is clamped between the upper and lower walls I920 of a generally U shaped die casting 2i which extends from the rear wall 22 of a closed casing 23. The side walls 24-25 (Fig. 4) of casing 23 are secured by any suitable means (not shown) to the front wall 28 of chassis ill. The circuit i2 is tuned by means of a cylindrical powdered iron core 21 which is mounted on a push rod 28, the portion 29 of rod 28 on which the core 21 is mounted being of i sulation' material, as shown. Push rod is is a ball 4i is seated. the ball being carried by a bushing 42 and biased inwardly by a spring 43. The bushing 42 is secured to the rear wall 22 of casing 24 by the screws 44 and is provided with a bore Illa 'which'assists bore ll in supporting and guiding the push rod 28 during its longitudinal adjustment.

Referring to Figs. 1, 4 and 10, the front end of push rod it engages a floating cam C which is mounted for both rotation and longitudinal movement, the cam being rotated by a gear 45 which is driven by a meshing gear 46 the latter gear being driven by a tuning knob 41 through connections to be later described. Rotation of the cam C by the knob 41 and gear 45 serves to rapidly tune the resonant circuit l2 in steps through a large range of frequencies in a man-' ner to be later described. The cam C is also adapted to be moved bodily in a rearward direction to tune circuit l2 through a smaller range of frequencies by means of an adjusting screw 44 of fine pitch as, for example, '75 threads per inch. Screw 44 may be suitably made of monel metal, and at its rear end has rigidly secured thereto a button 49 of tough steel such as Ohio Airdy (see Fig. 12). Button 48 has a conical shaped intermediate portion 50 and terminates in a tip ii of reduced diameter, the rear end of a tip Ii being ground to have a smooth spherical curvature as indicated at 52, a suitable radius of such curvature being about 5 inches.

For a more detailed description of step cam C reference is made to Figs. 5, 6 and 7 wherein it is shown as comprising a disc shaped cam member 53 which is-preferably formed as a die casting of aluminum alloy having a composition of approximately 4% copper, 6% silicon and 90% aluminum. The rear face of cam disc 53 is provided with 24 steps of increasing thickness, a hardened steel ball 54 being secured in each step in a manner described in the above noted application. The balls are of the same diameter and are all disposed at the same radius from the center of cam disc 53, the bearing face of each ball being elevated exactly .010 inch above that of the next adjacent ball. As the cam is rotated, the balls are arranged to come successively into. engagement with spaced apart surfaces 55 formed on the end of push rod 28 (see Figs. 10

surfaces are of the same length to permit of their being conveniently lap finished simultaneously to a smooth finish, the radius of curvature of which is the same asthat of the balls. 54.

From the upper surface ll the top of the push rod tapers gradually rearwardly as indicated at ll, Figs. 10, 12 and 15. By this construction the position of the push rod at each setting of the cam is not determined by the high point of the ball, which tends to wear away more rapidly than other portions thereof, but by lower zones on the ball which have line engagement with the curved surfaces Bl. The construction also operates substantially the same in either direction so that the amount of torque required to be applied to the tuning knob 41 (Fig. 4) is substantially the same whether the push rod 28 is to be stepped forwardly or rearwardly by the cam.

Cam disc 53 is mounted for rotation and longitudinal movement on a horizontal spindle 59 whose rear end is secured in a bore ill provided in the vertical wall 22 (Fig. 6), the spindle being secured by having its end riveted over, as indicated at Bl. A threaded screw 62 passes through an opening 63 provided at the center of cam disc 53, the front end of screw 82 having an enlarged cylindrical head 84 which is provided with a short shoulder 65 which engages the front face of gear 45. A member 66 formed of resilient material as, for example, Phosphor bronze is disposed between gear 45 and a forwardly extending shoulder 81 provided at the center of cam disc 53. The several parts comprising the cam are secured together by a pin "a and a nut 88 which is threaded on the rear end of screw 62. A plurality of radial slits 69 are formed in member 66 which define a series of radially extending spring fingers 10, the outer end of each finger being provided with a short lug H. The front face of each spring finger near the outer end thereof is cut away to form a tapered surface 12 which is deepest at the outer end of the finger, as indicated at 13, and merges with the front surface of the finger in the curve I4 (Fig.

Means is provided for adjusting the thickness of cam C at the region of each ball 54. For this purpose the front surface of cam disc 53 is provided with a plurality of radially extending grooves 15 whose bottom walls I6 are inclined at a small angle as, for example, 2 degrees with reference to a vertical plane through the front face of the cam disc, this angle being exaggerated in the drawings for the purpose of clarity. Disposed in each of the grooves 15 is a thin compensating block 11 whose front surface is vertical and whose rear surface is tapered at an inclination of the order of 2 and is seated against the bottom wall 18 of the groove II. The rear surface of each block 11 is biased against the bottom wall 16 of its groove by means of one of the spring fingers 10, the lug II on which bears against the front surface of the compensating block, as shown in Figs. 5 and 6. Each block 11 is also held firmly in engagement with one side wall of its groove 15 by means of a spring 18 which is disposed between the side of the compensating block and the other side wall of the groove 15. The ends of spring 18 engage the ends of the compensating block 11 and in the from of the invention shown in Figs. 5 and v7 the inner end 18 of the spring lies flat against the inner end of the compensating block while the outer end 80 of the spring is in the shape of a hook, thereby providing an opening 8| between the outer end of the block and the end of the spring for a purpose to be later described. Since a compensating block I! is provided opposite each ball 54 it will be readily understood that as a block is moved radially inward within its groove 1!, due the gradual slope of the bottom wall ll of the groove, the distance between the ball 54 and the front vertical surface 82 of the block will be gradually increased, the compensating blocks thus affording a means for readily regulating the thickness of the cam within close limits at the region of each ball. The spring fingers 10, together with the springs I8, provide means for retaining the compensating blocks in their.adjusted positions, so that they do not move within their grooves during operation of the radio device.

Modified forms of springs are shown in Figs. 8 and 9. In the form shown in Fig. 8 the outer end of the spring terminates in a short fiat portion 83 which rests against the outer end of the compensating block TI so that if the block is pushed inwardly along its groove by means of a tool applied to the outer end 80' of the spring, all the applied force will be transmitted to the outer end of the block 11 and none of it trans mitted to the bowed portion of the spring. Such force applied to the bowed portion might set up a strain therein which would remain after the adjustment of the block and possibly cause the block to creep slightly along its groove 15 for a short distance upon the operation of the device. Such creeping of the compensating block would change the thickness of the cam slightly at this region and introduce a slight error in the setting of the push rod 28.

In the form of the invention shown in Fig. 9 the outer end 80" of spring 18" is straight and bears against the outer end of compensating block 11" so that any radial pressure applied to the end 80" of the spring is entirely taken up by the compensating block, and none of it is transmitted to the bowed portion of the spring. Thus no strain is stored up in the bowed portion which might tend to cause the compensating block to creep along its groove 15 slightly during the operation of the device. An opening 84 is provided in the outer end of the block 1'!" wherein the end of a too may be inserted to pull the block outwardly along its groove in the cam disc 53 for a purpose to be later described.

For transmitting the rotation of knob 41 (see Figs. 4 and 17) to gear wheel 48 and cam C, the gear 46 is secured to a shaft 85 as by a pin 86, the front end of shaft 85 being enlarged to form a disc 81 to the rear surface of which a Bakelite gear wheel 88 is secured by screws 88. The shaft 85 is Journaled for rotation in a tubular bearing 90 which is secured to the front wall 2! and extends through an opening 9! provided in this wall. Gear wheel 88 is in turn driven by a Bakelite gear wheel 92 which is secured to an enlarged central portion 93 of a hollow supporting hub 94 as by screws 94. The hub 94 is journaled for rotation on a short spindle 95 whose rear end extends through an opening provided in the wall 28 and is threaded as at 98, to receive a lock nut 81 which secures the spindle 95 in position. At its front end the hub 94 is provided with a pair of outwardly extending, radially disposed thin fins 98 whose outer ends are seated in a pair of shallow grooves 99 formed in a rubber supporting collar Hill. The collar I00 is in turn supp rted in a rotatable metallic supporting cup illi which is disposed in a circular opening I02 in the front panel I03 of a closed casing I04 in which the radio chassis I0 is resiliently supported for a limited degree of movement in all directions. The cup "ii is provided with an outwardly extending flange I03 which bears against the rear surface of the wall I03 and tuning knob 41. is provided with a threaded screw I03 for securing it to the cup IN, the rear face of knob 41 bearing against the front surface of panel I03, as shown in Fig; 4. Cup IOI near its front end is provided with a reduced shoulder portion I01 which bears against the front surface of rubber collar I to take up the end thrust of such collar in a forward direction. Cup IOI is shown as provided with four fins I08 (see Fig. 17) which extend radially inwards into corresponding grooves I03 provided in the rubber collar I00 so that rotation of the cup MI is transmitted to the rubber supporting collar I00 and by the latter through the fins 33 to the hub 34 and gear wheel 32. It will be observed in Fig. 4 that there is a clearance space -IIO provided between the end of spindle 35 and the interior end wall III of the cup "II.

From the above description it will be readily,

understood that the rubber collar I00 not only serves as a portion of the means used to transmit the rotation of tuning knob 41 to cam C, but also serves as a means for resiliently supporting a portion'of the chassis I0 at its front end with limited freedom of movement in all directions within the casing I04.

The means for resilientl 'supporting the rear end of the chassis for limited movement in all directions comprises a vertically disposed narrow plate II2 (see Figs. 2 and 4) to the upper end of which is secured a short cylindrical stud II 3 which is disposed in a central opening Il4 formed in a rubber supporting collar I I5. The stud I I3 has an enlarged flange portion H3 whose rear surface bears against the front surface of rubber collar H5 and transmits any 'rearward thrust of the chassis I0 to the center portion of the rubber collar. Such end thrustis taken up by a shoulder III provided on a hollow supporting cup II8 in which the collar H5 is seated and which is secured in a fixed position on the rear vertical wall II3 of casing I04 by a threaded screw I20.

For indicating the tuning of circuit I2 and the setting of core 21 as determined by the rotation of knob 41, gear 83 drives a Bakelite gear wheel I2I (see Figs. 1 and 4) to whose front face is secured by pins I22 a .thin metallic disc I23. Disc I23 carries near its outer periphery a Bakelit ring I24 whose front face constitutes a graduated dial I25, the graduations being discontinuous and shown as extending from 100 to 124 megacycles, see Fig. 1.- These graduations appear behind a glass I23 set in a window opening I21 provided in front panel I03, 9. suitable index mark I28 being provided on panel I03. At their centers gear wheel HI and disc I23 are secured to a hub I23 which is mounted for free rotation on the peripheral surface of the rear end portion of a hollow outboard bearing member I3I. Bearing member I3I is secured in fixed position on th chassis wall 23 by a retaining collar I32 which extends inwardly and overlies an outwardly projecting flange I33 formed at the rear end of member I3I. Collar I32 is secured in position on wall 23 by any suitable means, as by the screws I34. The rotation of the cam C and the dial I are limited to less than one revolution by two stops I on the gear I2I which engage with a pin I30a fixed on the plate 28. p

Referring to Figs. 4, 12 and 13, adjusting screw 48 is supported for rotation in a hollow supporting nut I35 which is-provided with an outwardly extending fiange I33 through. which pass securing ance space between the center portion of adjusting screw 48 and the center portion of the nut.

The front and rear end portions I33 and I of the nut are interiorly threaded to receive the screw 48 and at the bottom each of the end portions I30I40 is cut vertically as indicated at I, Fig. 13, and is also cut vertically in a direction normal to the axis of screw 48 at a distance from the'end of the nut as indicated at I42. Two threaded, loading fingers I43 and I44 are thus formed which may be forced slightly inwardly to load the screw 48 and eliminate the major portion of the backlash between the screw and nut. Each end portion I33 and I,40 of the nut has its outer surface cut away to receive a pair of clamping collars I45--l43 which are slightly elliptical in shape before being placed in position on the nut portions I33 and I40, the eccentricity of the members 'I45-I43 being shown on an exaggerated scale in Fig. 14 in which the dot and dash line represents a circle. Each clamp member I45 and I43 is provided with a pair of shallow bores I4l adapted to receive the end of a spanner wrench used for rotating the clamp to bias its loading finger I43-I 44 into firm engagement with the threads of screw 43. It will also be understood that any wear of the threads of screw 48 resulting from the continued use of the device ma be taken up by slightly rotating the clamping collars I45 and I43 on the nut. The illustrated means for supporting the adjusting screw by nut portions which engage the threads of the screw at spaced apart regions thereof provides against any sidewise, vertical or endwise undesired motionof the screw in the nut so that only the desired longitudinal movement of the screw due to its rotation is secured.

Screw 48 is rotated by mean of a short shaft I48 whose rear end extends into a bore I43 provided in the screw and is a drive fit in the bore (see Figs. 4 and 12). Shaft I48 is firmly supported for rotation in a forwardly projecting hub I50 formed on the outboard bearing member I3I and which is connected thereto by 8- radial flange I5I. The front end of shaft I48 (see Figs, 3 and 4) is threaded as at I52, and is provided with a thin longitudinally extending slot I53, a nut I54 being screwed on to the threaded end portion thereof. Nut I54 engages the front end of a thin fiat key I55 whose inner end I53 becomes seated against the rear wall I51 of the slot I53. The outer ends I51 of the key are disposed in a narrow slot I58 formed in the front-end of a rotatable hollow cup member I53 which is supported for rotation on the supporting hub I50. Cup I53 has secured to itsouter periphery a thin circular disc I30 whose front surface constitutes a graduated dial I3'I whose graduations are continuous and disposed closely adjacent to those of the dial I25 and appear through a circumferentially extending portion I32 of the window opening I2'l (see Fig. 1). An index mark I33 is formed on the panel I03 adjacent to the graduatipns of dial I3I. The hollow cup I53 is rotated by means of a rubber supporting collar I34 which is provided with a in a bore I 10 provided in the front panel I03, the cup I69 having at its end an outwardly turned flange I1I which engages the rear face of the panel. The cup I69 is in turn rotated by a tuning knob I.12 which is secured to the cup by a set screw I13, the rear face I14 of the knob I12 being ulSDOSEd. against the front surface of the vertical panel I03, as shown in Fig. 4.

The front face of rubber collar I64 near its periphery bears against a shoulder I15 provided on the retaining cup I69. The rubber supporting collars I and I64 thus provide means for resiliently supporting the front portion of the radio chassis I0 at spaced apart regions thereof with limited freedom of movement; in all directions within the casing I04 while the rubber collar II similarly supports the rear portion of the chassis. Any forward movement of the chassis which might result from shocks Or vibrations imparted thereto is limited by the rubber collars I00 and I64 which absorb the shock and transmit it to the panel I03, the portion of collar I64 within the shoulder I15 on cup I69 bulging forward slightly, a suitable clearance space I16 being provided beyond the front end of adjusting screw shaft I48 for this purpose. The portion of rubber collar I00 disposed inwardly of the shoulder I01 on cup IOI similarly bulges forward a slight amount. Any rearward movement of the chassis resulting from shock or vibration is limited and absorbed by the rubber collar II5, the portion thereof which is disposed inwardly of the shoulder II1 on supporting cup II8 bulging rearwardly a slight amount, a suitable clearance space I11 being provided at the rear of collar II5 for this purpose. Any vertical or sidewise movement of the chassis I0 resulting from shock or vibration is transmitted to and absorbed by all three of the rubber collars I00, H5 and I64.

The rotation of adjusting screw 48 and continuous dial I6I is limited to substantially threefourths of a revolution by means of a pin I18 (Figs. 4 and 19) which is set in the flange I5I and projects forwardly into a shallow circular groove I19 provided in the rear face of cup I59. A pair of spaced apart pins I80, I8I (Fig. 19) are set in the rear face of cup I59 and extend rearwardly into the groove I19 where one or the other of them comes into engagement with the pin I18 as the tuning knob I12 is rotated to its extreme position in one direction or the other. A thin washer I82 (Fig. 4) is interposed between the dial disc I60 and the flange I5I to separate the dial disc I60 slightly from dial disc I23 so that the two dials do not rub together.

Referring to Figs. 1 and 2, the ceramic block I6 is shown as also supporting a compressed powdered iron block I83 shown as having an arcuate upper face I84. The block I83 is adjustably secured in position on supporting block I6 by a pair of screws I85 which pass through narrow vertical slots I86 formed in the block I6.

A suitable material for the compensating blocks 11 is #440 stainless steel which has been hardened to a degree of 62 Brinell. The steel balls 54 are preferably nitrided to harden their surfaces while the push rod 28 may be made of Ohio Airdy steel. The nut I35 may be made of Tobin bronze, and the springs 18 and 33 of Phosphor bronze. The device is designed to prevent any change in position of substantial amount of the iron core 21 with reference to its coil I3 due to changes in temperature of the apparatus. This compensation is secured not by making the apparatus of relatively non-expanding material such as Invar,

but by assuring that the parts which determine the distance between core 21 and coil I3 and the front wall 26 expand and contract together by equal amounts so that the relative position of the core and coil remains unchanged.

In using the radio tuner the dial I25 is set at 124 and the dial I6I is set at 1000. The coil I3 is now adjusted lengthwise of push rod 23 by slightly spreading apart the upper and lower walls I9 and 20 of the die casting 2|, see Figs. 1, 2 and 4, a special expanding tool (not shown) being provided for this purpose, whereupon the coil supporting block I6 is slid along the walls I9 and 23 until the oscillator circuit I2 is tuned to exactly 125 megacycles, as indicated by the sum of the readings on the dials I25 and I6I. The expanding tool is then removed, whereupon the supporting block I6 becomes firmly clamped in posi tion by the walls of casting 2!, it being found that this clamping action is adequate to prevent the supporting block from moving thereafter even when the radio tuner is subjected to sudden shocks 0r considerable vibration. The core 21 is now in its extreme forward portion with reference to coil I3, cam disc 53 is in the position shown in Figs. 5, 6, 10 and 11, and the bearing surfaces 55 on the end of push rod 28 are in engagement with the lowest ball 54, as shown in Fig. 10. Knobs 41 and I12 are now rotated in a clockwise direction until dial I 25 reads and dial I6I reads zero, which adjustment mOVes the push rod 28 and core 21 to their extreme rearward osition. The iron block I83, see Figs. 1 and 2, is then raised or lowered until the oscillator circult I2 is tuned to 100 megacycles, whereupon the block is secured in fixed position by tightening the screws I85. The adjustment of this block has the effect of changing the slope of the tuning curve of resonant circuit I2. After such adjustment of the circuit to the indicated frequencies. rotation of knob I12 and adjusting screw 48 counterclockwise, as indicated by the arrow in Fig. 1, for a distance of one division on continuous dial I6I permits. the cam C and push rod 28 to be moved forwardly a distance .0001 inch, thereby tuning the circuit I 2 to a frequency of 100,010 kc. as determined by taking the sum of the readings on dials I25 and "H. The knob I12 is now rotated another dial division of dial IEI which causes push rod 28 and core 21 to be moved forwardly another .0001 inch under the bias of spring 33 and oscillator circuit I2 to be tuned to the frequency of 100,020'kc., as determined by adding together the two dial readings. When the knob I12 has thus been rotated through 100 dial divisions of dial I6I, the circuit I2 will be tuned to 101 megacycles and the iron core 21 will have been adjusted .010 inch forwardly of its initial position. By now rotating the knob I12 and dial I6I to their initial or zero positions, push rod 23 and core 21 will be moved rearwardly by screw 48 to their initial position, and the frequency of oscillator circuit I2 will again be 100 megacycles. By now rotating knob 41 counterclockwise, as indicated by the arrow in Fig. 1, until the outer dial I25 reads 101 megacycles, the cam disc 33 is rotated until the next lower ball 54 thereon comes into engagement with the bearing surfaces 65 of push rod 28. Under the bias of spring 33, the push rod is moved forwardly a distance of .010 inch and causes the circuit I2 to be tuned to the indicated dial reading of 101 megacycles. Any slight inaccuracy of the tuning to this frequency may be compensated for by the operator withdrawing a screw I81 from a threaded opening I88 provided in the cam casing 28, see Figs. 2 and 4. A special micrometer head (not shown) provided for this purpose is now inserted in the opening I88, the end of the micrometer screw engaging the end 88 of spring 18, Fig. '7, and by rotatin the micrometer screw the compensating block 11 which is in engagement with curved end 82, Fig. 12, of adjusting screw 48 is moved inwardly within its groove I5 to move cam disc 88 and push rod 2a rearwardly a suitable amount until circuit I2 is tuned to the desired frequency. Should the compensating block be adjusted inwardly in its groove slightly too far, the micrometer head is withdrawn from the opening I88 and a tool inserted therethrough which has a projecting end portion which may be inserted within the openin 8|, Fig. '7, of spring 18, then by pulling on the tool the compensating block may be pulled outwardly in its groove a substantial amount. After removing such tool, the micrometer head is again inserted in the opening I88 and the compensating block 11 moved inwardly in its groove by the micrometer screw until the correct resonant frequency of circuit I2 is secured. V

The radio tuner may. now be tuned consecutively through the next one hundred settings by rotating the knob I12 and dial I8I consecutively through one hundred divisions of this dial one by one until the dial reads 1000, when the circuit I2 will be tuned to 102 megacycles and push rod 28 will be .020 inch forwardly of its initial position. By now rotating knob I12 clockwise until continuous dial I8I reads zero and then rotating the knob 41 and dial I25 counterclockwise until a reading of 102 megacycles appears on this dial, the third ball 54 on cam disc 58 will have been brought into engagement with the bearing surfaces 55 on push rod 28 and the circuit I2 will be again tuned to 102 megacycles. Any slight inaccuracy of the tuning for this dial position may be corrected in the manner above described by adjusting the compensating block 11 which is now in engagement with the end 52 of button 48 in its groove by the micrometer device in the manner above described. By continuing this operation repeatedly the circuit I2 may be tuned through all the frequencies corresponding to the 2500 dial setting and the tuning of the circuit adjusted to the desired value for each of the divisions on the outer dial I25 by adjusting the compensating blocks 11 in their grooves in the manner above described. It will be understood that, after all the compensating blocks have been appropriately adjusted, the screw I81 will again be screwed into the threaded opening I88, Figs. 2 and 4, thereby sealing the cam C, adjustin screw 48 and their associated parts in the casing 23 against the entrance of dust or dirt Particles which might otherwise collect on different parts of the mechanism and destroy its accuracy by interfering with its proper operation. The radio tuner is then ready for operation, and it is found that within the short interval of four seconds the oscillator circuit i2 may be readily tuned from any frequency to any of the otherfrequencies corresponding to the 2500 difierent dial readings.

If it is desired to advance the push rod 28 rearwardly step by step by rotating the knob 41 and cam C clockwise, when the rotation of the cam is commenced the tapered surface 12 on the front of spring finger (Figs. 5, l0 and 12) immediately comes into engagement with the conical surface 58 of button 48 and exerts a component of force on the spring finger and its underlyin compensating block 11 which pushes the cam C rearwardly along its supporting spindle 88 into the position shown in Fig. 12, so that the end ll of button 48 clears the edge of the next adjacent compensating block as this block is brought into position by the rotation of the cam. When the front face 82 of the next compensating block has been brought opposite the curved surface 82 on the end of button 48, the tapered surface 12 on its spring finger 18 rides down the conical surface 88 as the rotation of cam C continues and the cam moves forwardly under the bias of spring 88 (Fi 4) until the spring finger is entirely clear of button, 48 and the front face 82 of the block is in engagement with the curved surface 82 deflnins the end of button 48.

Referring to Fig. 9, the compensating block 11" is adjusted inwardly along its groove 18 in the cam by placing the end of the aforedescribed micrometer screw in engagement with the flat end 88" of its spring, and then rotating the micrometer screw a suitable amount. Should the compensating block accidentally be moved too far inwardly, it may be withdrawn by placing the end of the aforementioned tool in the hole 84 in the block and pulling the block outwardly in its groove, after which the block may be again moved inwardly by the micrometer screw to thecorrect position.

While the invention has been illustrated in connection with the tuning of an oscillator circuit, it will be understood that additional iron cores may be mounted on push rod 28 to tune the radio frequency circuits of a radio receiver or other radio device, in the manner illustrated and described in my aforementionedapplication. Furthermore, the push rod 28 may be used to operate an adjustable gage used for measuring the size of articles as illustrated in my aforementioned application or for operating the controlled element of any otherdevice which is required to be adjusted within close limits.

While I have illustrated my invention as including a step cam as a spacing means for effecting different positions for the operated rod or member 28, each of which cam steps as described difiers uniformly in thickness from the preceding one of said cam steps, it will be understood that for some purposes these cam portions may have any desired diiferent thicknesses to,

meet the requirements of different purposes of use, whether the limited amount of movement of further be understood that my invention is adapted for use where lesser degrees of accuracy of movement are permissible than for the uses described. For example, for the purpose ,of the relatively general grading or grouping of objects as to size, or the resonant selection of radio stations from a relatively small group of such stations such as the broadcast band, the high degree of accuracy described may not be required. In such cases the spacing means or cam C need not be provided with the balls 54, but may be an integral structure made from a single metal block with a degree of accuracy, in any case, that is commensurate with the intended purposes of the structure.

I have described what I believe to be the best embodiments of my invention. I do not wish, however, to be confined to the embodiments shown, but what I desire to cover by Letters Patent is set forth in the appended claims.

I claim:

1. A device for adjusting a driven member longitudinal ly comprising, in combination, a spacing cam having its rear face provided with a plurality of spaced apart balls disposed at successively increasing elevations, supporting means arranged to support said cam for both rotation and bodily movement, means for rotating the cam to bring successive balls thereof into engagement with said driven member, an adjusting screw having a fine pitch and supported with its rear end in engagement with the front surface of the cam, and a control knob connected to and arranged to rotate said screw.

2. A device as claimed in claim 1 in which the driven member is in alignment with the adjusting screw whereby the stress applied to the cam by the adjusting screw is transmitted directly through the material of the cam to the driven member.

3. A device as claimed in claim 1 in which the adjusting screw is supported in a nut having interiorly threaded portions which engage the threads of the screw at spaced apart regions thereof, and which includes clamping means arranged to bias the threaded nut portions into firm contact with the threads of the adjusting screw and thereby minimize the amount of backlash.

4. A device as claimed in claim 1 in which a stop device is provided to limit the rotation of the adjusting screw to less than a full revolution thereof, and a graduated dial is connected to the adjusting screw to indicate the setting of the driven member.

5. A device as claimed in claim 1 in which the increment in elevation between successive balls is substantially constant, a graduated rotatable dial connected to the cam and a second graduated rotatable dial connected to the adjusting screw, the graduations of both said dials being in terms of the same unit of measurement whereby the setting of the driven member may be determined by taking the sum of the dial readings.

6. A device as claimed in claim 1 in which the front face of the cam is provided opposite a plurality of the balls with surfaces slightly inclined with reference to a vertical plane passing therethrough, a plurality of thin tapered compensating blocks seated against said inclined surfaces and adapted to be displaced thereon, and means for retaining said compensating blocks in desired positions on the cam.

7. A device as claimed in claim 1 in which the front face of the cam is provided opposite a plurality of the balls with shallow grooves whose bottom walls are slightly inclined with reference to a vertical plane passing therethrough, a plurality of thin tapered compensating blocks seated in said grooves, and spring means for retaining said compensating blocks in desired positions in the said grooves.

8. A device as claimed in claim 1 in which the adjusting screw near its rear end is provided with a, curved surface adapted to engage spaced apart areas provided on the front face of the cam and push the cam rearwardly so that its front surface is momentarily out of engagement with the end of the adjustingscrew in response to the rotation of the cam.

9. A cam having its rear face provided with a plurality of balls which are spaced apart by substantially equal distances and disposed at successively increasing elevations, the increment in elevation between successive balls being substantially constant, and means for regulating to close limits the thickness of the cam in the region of each of the balls, said last named means comprising a plurality of grooves formed in the front face of the cam and slightly tapered compensating blocks seated in and adapted to be moved along said grooves.

10. A cam as claimed in claim 9 in which the cam is disc shaped and the grooves are disposed substantially radially of the disc.

11. A cam disc mounted for rotation about a horizontal axis, said cam disc having its rear face provided with a plurality of balls which are spaced apart by substantially equal distances and disposed at successively increasing elevations, the increment in elevation between successive balls being substantially constant; the front face of the cam being provided opposite a plurality of the balls with surfaces slightly inclined with reference to a vertical plane passing therethrough, a plurality of tapered compensating blocks in desired positions on said inclined surfaces whereby the distance between the front face of each compensating block and the rear face of the corresponding ball may be adjusted to close limits.

12. A cam disc as claimed in claim 11 in which means are provided for retaining the compensating blocks in position comprising a. plurality of fingers formed of resilient material and engaging the front faces of the compensating blocks to bias their rear faces against the said inclined surfaces.

13. A cam as claimed in claim 11 in which the balls and compensating blocks are composed of materials having a substantially higher degree of hardness than the material of the cam disc itself, the balls being hard enough to be driven into the material of the cam disc without suffering any substantial distortion, and being so driven into the material of the cam disc.

14. A cam comprising a disc mounted for rotation about a horizontal axis, said disc having its rear face provided with a plurality of balls which are spaced apart by substantially equal distances and disposed at successively increasing elevations, the increment in elevation between successive balls being substantially constant; and means for regulating to close limits the thickness of the cam in the region of several of the balls, said last named means comprising a plurality of substantially radially disposed grooves formed in the front face of the disc, the bottom walls of said grooves being slightly inclined with reference to a vertical plane passing therethrough; slightly tapered compensating blocks seated in said grooves and a, plurality of springs arranged to bias the compensating blocks against the sides of the grooves, the outer ends of the springs being in engagement with the outer ends of the compensating blocks whereby any compensating block may be moved inwardly in its groove in response to the application of pressure to the outer end of its spring.

15. A cam as claimed in claim 14 in which the inner ends of the springs are in engagement with the inner ends of the compensating blocks whereby any compensating block may be moved outwardly in its groove in response to a pull on the outer end of its spring.

16. A cam as claimed in claim 14 in which the outer ends of at least some of the springs are hook shaped.

17. A cam as claimed in claim 14 in which at least some of the compensating blocks are provided with apertures adapted to receive the end of a tool whereby a compensating block may be moved outwardly in its groove in response to a pull on the tool.

18. A stepped spacing cam comprising a main body member and a plurality of tapered compensating blocks carried by the body member in engagement therewith, the surface of the body member adjacent each compensating block having a slope substantialhr complementary to the taper of said block. whereby thecombined thick ness of said body member and any block may be adjusted by the adjustment of said block lengthwise of said slope.

19. A cam-like member having a rear surface provided with a plurality of spaced apart bearing areas of diiierent elevation and adapted to suece'ssivelyengageadrivenmemberinresponseto movement of the cam, the front face of the cam' wherebythethicknessotthecamintheresionot each of the bearing areas may be regulated to close limits in response to the adjustment of the compensating blocks alons the said inclined surface or surfaces.

. SIDNEY Y. WHI'IE. 

